undersink water heater

Robbie71

10 L Atlantic undersink

how do i connect the 1/2" pipe from the pressure relief valve to the waste pipe from the sink.

I am thinking - put a T , a P trap and a small upstanding pipe

is there any other way ?

LIFFY FISHING

Robbie71 wrote: »

10 L Atlantic undersink

how do i connect the 1/2" pipe from the pressure relief valve to the waste pipe from the sink.

I am thinking - put a T , a P trap and a small upstanding pipe

is there any other way ?

Just check it out, pressure relief valves generally go to athmosphere not a drain

shane0007

It should not be piped into your waste pipe. It should be piped externally to discharge at low level or back into face the wall externally. It is also best practice to pipe it via a tundish for inspection.

Robbie71

Its in an office apartment with no external walls .
Water pressure is high so everytime the tap is turned on or off there is a blast of water from the PRV . This happens even if the heater is not turned on.
Already the prv stayed open and nearly drenched the place.
I cant trust leaving it open to the atmosphere

The only drain point is the sink waste.

Unvented cylinders/water heater discharge pipework must be fitted with a tundish and terminate in a safe manor, they should never terminate to atmosphere or have plastic pipe anywhere on the discharge pipe work unless fitted with a HEPvO waste valve(link below) which can then allow a waste or plastic pipe to be used.

When fitting unvented appliances expansion, temperature and pressure must be taken in to consideration, not doing so can and does lead to tears and big payouts or customers getting hurt.


http://www.redbooklive.com/pdf/042-97.pdf

Robbie71

Robbie71 wrote: »

Its in an office apartment with no external walls .
Water pressure is high so everytime the tap is turned on or off there is a blast of water from the PRV . This happens even if the heater is not turned on.
Already the prv stayed open and nearly drenched the place.
I cant trust leaving it open to the atmosphere

The only drain point is the sink waste.

Anything over 3 1/2 bar incoming must be fitted with a pressure reducing valve, a valve lifting is a indication of a defect and must be treated as a warning, to do otherwise leaves you liable for any damage caused.

Undersink water heater installation is formatted by using UK water regs, these regs are then used to determine fault by insurance company's, if you don't fit to UK water regs you are liable for any damage caused.

shane0007

Robbie71 wrote: »

Its in an office apartment with no external walls .
Water pressure is high so everytime the tap is turned on or off there is a blast of water from the PRV . This happens even if the heater is not turned on.
Already the prv stayed open and nearly drenched the place.
I cant trust leaving it open to the atmosphere

The only drain point is the sink waste.

I think you should be paying attention to the cause of the problem rather than hiding the symptom!

Robbie71

Ok, so if I do put in a pressure reducing valve ,


where do i point the prv outlet pipe ?
I cant put it externally ,don't want it internally in case a fault causes a flood while office is empty,

How do I connect it so any discharge does'nt end up on the floor?

Robbie71

Robbie71 wrote: »

Ok, so if I do put in a pressure reducing valve ,


where do i point the prv outlet pipe ?
I cant put it externally ,don't want it internally in case a fault causes a flood while office is empty,

How do I connect it so any discharge does'nt end up on the floor?

If you read my above post i'v answered that for you;)

shane0007

You are still just hiding the symptoms of a defective prv. That unit can handle pressure of upto 5 bar without a pressure reducing valve but local regs must be obeyed. The unit should be serviced by a competent person. Service & commissioning instructions are in the MI's. if you are using the HEPvO then I would recommend the use of a tundish between the discharge pipe & the HEPvO.

shane0007

Are you 2 related?

shane0007

shane0007 wrote: »

You are still just hiding the symptoms of a defective prv. That unit can handle pressure of upto 5 bar without a pressure reducing valve but local regs must be obeyed. The unit should be serviced by a competent person. Service & commissioning instructions are in the MI's. if you are using the HEPvO then I would recommend the use of a tundish between the discharge pipe & the HEPvO.

It doesn't matter what the unit can handle, due to the lack of regulations here UK and manufactures guidelines(which mirror UK regs) are used as a benchmark when installations are inspected.

If you look at a combination valve on a unvented cylinder they are rated to 3 1/2 bar as its the industry standard.

The Tundish ting I'll agree with:)

shane0007

shane0007 wrote: »

Are you 2 related?

That's right, we're twins who have fallen out over a woman and now only communicate on boards.

shane0007

shane0007 wrote: »

You are still just hiding the symptoms of a defective prv. That unit can handle pressure of upto 5 bar without a pressure reducing valve but local regs must be obeyed. The unit should be serviced by a competent person. Service & commissioning instructions are in the MI's. if you are using the HEPvO then I would recommend the use of a tundish between the discharge pipe & the HEPvO.

Erm.... Did I mention local regs? Hmmm....
Mr Grumpy

shane0007

gary71 wrote: »

That's right, we're twins who have fallen out over a woman and now only communicate on boards.

At least you can communicate....
See there is therapy to be found here! But I am saying nothing else in case the thread is closed before closure is achieved.

shane0007

shane0007 wrote: »

Erm.... Did I mention local regs? Hmmm....
Mr Grumpy

Grumpy would be my middle name.

3 1/2 bar is the highest pressure you can have, anything higher must be reduced to 3 1/2bar, I would be nervious around any heater being fed by a 5bar mains supply.

http://www.redring.co.uk/media/uploads/5782144_MW%20&%20EW%20RANGE.pdf

shane0007

gary71 wrote: »

http://www.redring.co.uk/media/uploads/5782144_MW%20&%20EW%20RANGE.pdf

Has one without expansion vessel 3.5 bar pressure reducing valve if mains is >6 bar and one with expansion vessel 3.5 bar pressure reducing valve.

Robbie71

ok , I have to come clean.
I am really Gary71 . I just use robbie71 to ask the "thick questions" to keep my credibilty.
The only problem is I reply to myself sometimes.
I also find I'm much more popular as robbie71

Dtp79

Robbie71 wrote: »

ok , I have to come clean.
I am really Gary71 . I just use robbie71 to ask the "thick questions" to keep my credibilty.
The only problem is I reply to myself sometimes.
I also find I'm much more popular as robbie71

Jays us I'm actually confuses here now. Don't know if you're actually telling the truth!

Dtp79

Dtp79 wrote: »

Jays us I'm actually confuses here now. Don't know if you're actually telling the truth!

Shane can be a bit confusing alright:D

Or am I Shane:cool: too, we've never been seen in the same place:eek:

shane0007

shane0007 wrote: »

Has one without expansion vessel 3.5 bar pressure reducing valve if mains is >6 bar and one with expansion vessel 3.5 bar pressure reducing valve.

The industry standard is 3 1/2 bar, some manufactures will give their own values but it's not always like for like as in the UK temperture/pressure safety valves can be fitted as well as a 6 bar blow off, there is no requirement for T/P valves on under sink or wall mounted water heaters in Ireland unfortunately which can lead to plastic pipes spliting causing mayhem.

I would always advise the limiting of water pressure to a heater to 3 1/2 bar for safety.

Dtp79

gary71 wrote: »

The industry standard is 3 1/2 bar, some manufactures will give their own values but it's not always like for like as in the UK temperture/pressure safety valves can be fitted as well as a 6 bar blow off, there is no requirement for T/P valves on under sink or wall mounted water heaters in Ireland unfortunately which can lead to plastic pipes spliting causing mayhem.

I would always advise the limiting of water pressure to a heater to 3 1/2 bar for safety.

Ok thanks Shane

corkgsxr

Unless its a high pressure tap 1 bar is loads

Dtp79

What size expansion vessel are we talkin bout here?

Dtp79

Dtp79 wrote: »

Ok thanks Shane

You watch, I'll be on in a minute with a contrary rebuff because Shane is my annoying persona, which I use when I really want to twist someone's mellons.

shane0007

Ah, but what would Robbie71 think of that? Would he agree with you? Or would you agree with yourself? Or would I agree with me?
Hmmmm.....

Dtp79

shane0007 wrote: »

Ah, but what would Robbie71 think of that? Would he agree with you? Or would you agree with yourself? Or would I agree with me?
Hmmmm.....

I agree with all 6 of u

Dtp79

Was chatting to baxi tech the other day. He reckoned if there's 4.1 metre of pipe out of the heater it's enough to take up the expansion

Dtp79

Dtp79 wrote: »

What size expansion vessel are we talkin bout here?

2lt, but manufactures tend to make their own for their heaters.

Dtp79

Dtp79 wrote: »

Was chatting to baxi tech the other day. He reckoned if there's 4.1 metre of pipe out of the heater it's enough to take up the expansion

The hot is not used when determining expansion requirements for a heater and i'v yet to see a heater with the required pipework on the mains supply.

These heaters can burst, the reason more don't burst is due to the low mains pressure in general, if fitted correctly damage is reduced if not insurance claims can at times be in the €10,000s:eek: I have seen a lot of installations and rarely are they right.

Dtp79

gary71 wrote: »

The hot is not used when determining expansion requirements for a heater and i'v yet to see a heater with the required pipework on the mains supply.

These heaters can burst, the reason more don't burst is due to the low mains pressure in general, if fitted correctly damage is reduced if not insurance claims can at times be in the €10,000s:eek: I have seen a lot of installations and rarely are they right.

Why don't they just supply a vessel with the unit when sold?

Dtp79

Dtp79 wrote: »

Why don't they just supply a vessel with the unit when sold?

Why don't installers ask for them? €€€ i'v been banging on on about this for the last 10 years and most installer are not interested in fitting the heaters properly and customers aren't interested in paying to have the job done properly.

The reason they don't put them in the box is not all installations require a expansion Vessal or pressure reducing valve, it's up to a installer to determine what he needs and then get it.

Robbie.G

gary71 wrote: »

Why don't installers ask for them? €€€ i'v been banging on on about this for the last 10 years and most installer are not interested in fitting the heaters properly and customers aren't interested in paying to have the job done properly.

The reason they don't put them in the box is not all installations require a expansion Vessal or pressure reducing valve, it's up to a installer to determine what he needs and then get it.

Calm down Shane

Dtp79

gary71 wrote: »

Why don't installers ask for them? €€€ i'v been banging on on about this for the last 10 years and most installer are not interested in fitting the heaters properly and customers aren't interested in paying to have the job done properly.

The reason they don't put them in the box is not all installations require a expansion Vessal or pressure reducing valve, it's up to a installer to determine what he needs and then get it.

Jesus tony I was only asking a question!!

Dtp79

Dtp79 wrote: »

Jesus tony I was only asking a question!!

I get so much agro from installers over bloody water heaters it's enough to drive all of me demented:eek:

Irish Steve

Robbie71 wrote: »

ok , I have to come clean.
I am really Gary71 . I just use robbie71 to ask the "thick questions" to keep my credibilty.
The only problem is I reply to myself sometimes.
I also find I'm much more popular as robbie71

Don't worry. It's when you start arguing with yourself the trouble is starting.

Just be VERY careful when you start losing the argument.

mylesm

is it possible to install one of these on the hot pipe from Hot Water cyclinder put it under sink and put hot pipe through it this means its open vented all the way back to attic also supply pressure would be low so risk of leaks less

If immersion is on hot water will just come through it and if immersion is off this heater will heat water anything wrong with this scenario

mylesm

mylesm

mylesm wrote: »

is it possible to install one of these on the hot pipe from Hot Water cyclinder put it under sink and put hot pipe through it this means its open vented all the way back to attic also supply pressure would be low so risk of leaks less

If immersion is on hot water will just come through it and if immersion is off this heater will heat water anything wrong with this scenario

mylesm

The're mains fed unvented water heater and require certain things to be taken in to account for safety sake. Taking safety in to account the answer to your query would be no.

shane0007

Also the flow rate would be too slow therefore it would be continuously overheating itself.

mylesm

Thanks for that but wheres the safety issue if its open vented

gary71 wrote: »

The're mains fed unvented water heater and require certain things to be taken in to account for safety sake. Taking safety in to account the answer to your query would be no.

mylesm

Thanks for reply

But dont they heat up and then cut out on a thermostat so no matter what the flow the tank is still full of water so thermostat should look after Temp control

If flow rate was an issue then if some one turned tap on a little it would be the same problem but this does not happen

I can see how flow rate would be a problem on instantaneous heaters but not tank type

shane0007 wrote: »

Also the flow rate would be too slow therefore it would be continuously overheating itself.

mylesm

mylesm wrote: »

Thanks for that but wheres the safety issue if its open vented

It's mains fed which means it requires mains water.

mylesm

Thank Again

Not trying to be akward but why would it require mains water is it not the same as an immersion tank only smaller a tank with a heater and thermostat in most cases its mains fed with a pressure relief valve but i see nothing wrong with it being tank fed and open vented if thermostat fails heater boils and vents exactly like an immersion heater so am I missing something or is it just that they are always mains fed and no one gives it any thought

gary71 wrote: »

It's mains fed which means it requires mains water.

shane0007

mylesm wrote: »

If flow rate was an issue then if some one turned tap on a little it would be the same problem but this does not happen

They are not designed for that. It would over-shoot its temperature especially after a couple of short off-takes. Open hot tap, over-shoots heat. Turn off tap & then on again. It would soon have scalding water.

mylesm

mylesm wrote: »

Thank Again

Not trying to be akward but why would it require mains water is it not the same as an immersion tank only smaller a tank with a heater and thermostat in most cases its mains fed with a pressure relief valve but i see nothing wrong with it being tank fed and open vented if thermostat fails heater boils and vents exactly like an immersion heater so am I missing something or is it just that they are always mains fed and no one gives it any thought

Plenty of thought has gone into it.

What experience do you have on unvented water heaters?

There are other reasons but the simplest reason for why they require mains water is the heater needs to be full of water to work safely, to fill fully requires the pressure from mains water, if you feed it from a tank or pump they can remain half empty allowing for a increased risk of scolding or burst pipes as the safety stat can be sitting above the line of the half filled heater.

mylesm

[

Thanks
I have no experience of unvented heaters and am only trying to understand the way they work and discussing it but is the way I was talking about connecting not making it a vented heater just like an immersion and will attic tank not fill it the same way it fills the immersion tank after all is it not the same as a small immersion under the sink if it's open vented

Thanks

QUOTE=gary71;85718633]Plenty of thought has gone into it.

What experience do you have on unvented water heaters?

There are other reasons but the simplest reason for why they require mains water is the heater needs to be full of water to work safely, to fill fully requires the pressure from mains water, if you feed it from a tank or pump they can remain half empty allowing for a increased risk of scolding or burst pipes as the safety stat can be sitting above the line of the half filled heater.[/QUOTE]

mylesm

But there is no design to prevent someone doing short takeoffs so it could happen anytime but I think you need a minimum draw before thermostat cuts in and this prevents the issue of overheating due to small draws

QUOTE=shane0007;85718532]They are not designed for that. It would over-shoot its temperature especially after a couple of short off-takes. Open hot tap, over-shoots heat. Turn off tap & then on again. It would soon have scalding water.[/QUOTE]

shane0007

Because the short take offs are still high flow rate therefore the volume of water passing through the unit is higher.

It is the same principle between a T90 gravity fed shower & a T80 mains fed shower. You can't mix the two.

I'v seen numerous installations over the years that were tank fed, they didn't work properly and some led to scoldings.

Buy a water heater of your choice and fit it as per manufactures instructions, anything else is on you.